drop back to one, two or three minutea with many errors. This 

 behavior was not noted in any other group except in one or two 

 isolated cases. 



Twenty -eight rata v/ere used, fifteen males and thirteen 

 females, eight families being represented as iollows: 



BD ■'^6/3 CC2 V-Jo/s WG *AV'3 BD ^>e/;3 BH '^y^ff/^ BH ^H'^ V.B'^^ZL ^/o/^Total 



1 1 3 1 2322 15 



2 2 2 4201 13 



Total 1 3 5 3 6523 28 



Trials varied in number from fourteen to one hundred twelve, 

 absolute time varied from five and tv.o tenths seconds to twenty - 

 four and one tenth seconds, total time from eighty-two to nine- 

 hundred forty -nine minutea, and total distance from one-hundred 

 twenty-five and five tenths meters to nine-hundred and twelve 

 neters. As for previous groups trials bear little relation to 

 time or distance, but the proportion between total time and to- 

 tal distance is fairly constant. f3ee Table IV) The lowest 

 trial record was fourteen, and the time and distance records 

 for the rat making this record were also low. The lowest time 

 record, as 'Aell as the lowest distance record was made by a rat 

 finishing in twenty trials. The rat requiring the largest xium- 

 ber of trials (112) had a time record but little higher than 

 one which required only thirty-four trials, vrhile its distance 

 record was next to the highest. The highest time record was 

 that of a rat which finished in one hundred aeven trials, with 

 the next to the highest distance record, the higliest distance 



